RSC Mechanochemistry最新文献

Schiff base complexes, traditionally synthesized via time-consuming, solvent-intensive solution methods, are pivotal in coordination chemistry but face limitations in accessing diverse architecture and sustainable scalability. Mechanochemistry has emerged as a solvent-free alternative, yet its potential to drive multicomponent reactions with precise control over metal–ligand coordination modes remains underexplored. Herein, we propose a mechanochemical one-pot synthesis strategy that synergistically integrates condensation, metal coordination, and deprotonation–dehalogenation reactions to fabricate Schiff base Co(II) complexes. Utilizing adamantylamine, 5-halosalicylaldehyde, and CoCl₂·6H₂O as precursors, mechanical forces drive the self-ordering of building blocks, enabling ultrahigh selective coordination and complex chemical processes. The approach efficiently yielded 12 Co(II) complexes, including the κ¹-O-monodentate CoCl₂(HL)₂ and κ²-O, N-bidentate CoL₂, which are typically challenging to access via conventional solution methods. Remarkably, the reactions achieved full conversion within 10 minutes, underscoring the rapidity and sustainability of mechanochemistry. Mechanical activation unlocked dormant reactivity in reactants, facilitating pathways otherwise inaccessible in solution. Furthermore, reversible solid-state transformations between complexes were demonstrated through dehydrohalogenation–hydrohalogenation processes. Specifically, CoCl₂(HL)₂ is converted to CoL₂via cleavage of N–H and Co–Cl bonds and subsequent Co–N bond formation, while CoL₂ reverts upon HCl absorption during grinding. This work highlights the utility of mechanochemistry in simplifying synthetic procedures, enhancing reaction complexity, and enabling green, solvent-free syntheses. By elucidating pathways for one-pot synthesis and solid-state transformations, it establishes mechanochemistry as a versatile and sustainable route for designing advanced coordination complexes with tailored architecture.

We, herein, present a practical and straightforward alternative mechanochemistry-driven strategy for the regioselective amination of biologically promising 1,4-naphthoquinone scaffolds to access functionalised 2-amino-1,4-naphthoquinones under additive- and solvent-free conditions. The notable features of the present method are solvent-free synthesis, avoidance of any additive and heating, broad substrate scope, good yields, shorter reaction times (in minutes), reusability of the solid surface, gram-scale synthesis, a clean reaction profile, and operational simplicity. In addition, a series of new selenylated derivatives of some selected 2-amino-1,4-naphthoquinones were prepared as part of an extended synthetic application.

Highly selective and efficient reduction of nitroarenes has been achieved using iron powder and water under mechanochemical conditions. A wide spectrum of reducible functionalities remained inert under these sustainable and green reaction conditions. During the reaction, Fe powder partially converted into valuable Fe₃O₄ nanoparticles.

Unlike conventional modes of activation of reactivity, mechanochemical force provides facile and unique pathways. Extensive studies have been performed on the thermal and photochemical interconversions between benzene and its valence isomers. In this article, we show that mechanochemical pulling along 1,2- positions of triprismane (TP) can precisely control the outcome, namely, benzene (BZ) and/or Dewar benzene (DB), depending upon the strength of external force. Within the force range of 1.5–1.9 nN, DB is formed exclusively, whereas at forces exceeding ≥2.0 nN, BZ becomes the major product. Also, we report that on pulling across 1,4-sites of TP, BZ is produced exclusively when external force ≥1.8 nN. Ab initio steered molecular dynamics (AISMD) simulations on the force modified potential energy surfaces (FMPESs) for 1,2-pulling of TP reveal that DB becomes the minor product beyond external force ≥2.0 nN. The thermodynamically controlled product, BZ, is obtained as the major and sole product for stronger 1,2-pulling and 1,4-pulling respectively. The constrained geometries simulate external force (CoGEF) calculations fail to locate the kinetically trapped intermediate, DB, revealing the prowess of AISMD in revealing unique intermediates and fleetingly stable products in the course of mechanochemical reactions. Also, we demonstrate that the TP → BZ reaction, which demands significant thermal energy, can be induced mechanochemically.

In the present work, we report a sustainable, room-temperature mechanochemical approach for synthesizing functional silicon quantum dots (Si QDs) with tunable photoluminescence (PL) in the visible range. Using hydrogen silsesquioxane as a precursor, precise control over the size and surface chemical state of Si QDs is achieved through controlled ball-milling and subsequent chemical etching and hydrosilylation. Discrete element method simulations reveal that the cumulative supra-critical impact energy (E_sup), defined as the total impact energy exceeding a critical threshold (e_crit) required for chemical activation, plays a dominant role in driving the formation of Si radicals and Si–H bond cleavage, which are key steps in crystallite growth. Under high-energy milling conditions using larger balls, a significant portion of collisions exceed e_crit, thereby enhancing the efficiency of solid-state chemical reactions and leading to the formation of larger Si QDs. The PL red shift observed across blue-, green-, and red-emitting Si QDs is attributed to a size–surface coupling mechanism. For smaller Si QDs, PL originates from quantum-confined band-edge transitions and shallow surface states, enabled by high alkyl chain coverage. Larger Si QDs exhibit red-shifted, excitation-independent emission dominated by deep oxide-related surface states, stemming from enhanced oxidation and reduced organic passivation. These findings highlight the interplay between mechanical energy input, structural/size evolution, and surface chemistry in tailoring the optical properties of Si QDs.

The mechanochromic properties of polymer particles crosslinked by difluorenylsuccinonitrile (DFSN), a radical-type mechanochromophore, are reported in relation to particle size and glass transition temperature. DFSN-crosslinked nanoparticles and microparticles were prepared via emulsion polymerization and suspension polymerization of vinyl monomers, respectively, using a DFSN-containing crosslinker. Mechanical grinding of the prepared white particles induced a pink coloration, originating from cyanofluorenyl (CF) radicals generated by the mechanically induced homolysis of DFSN units within the particles. The mechanochemical response of the particles was evaluated using scanning electron microscopy and electron paramagnetic resonance spectroscopy, revealing that microparticles exhibited a stronger response than nanoparticles due to the differences in pulverization behavior. The mechanochemical response also showed a strong correlation with the glass transition temperatures of the particles, highlighting the importance of polymer chain mobility in the mechanochromic properties of the developed polymer particles.

Correction for ‘Mechanochemical kilogram-scale synthesis of rac-ibuprofen:nicotinamide co-crystals using a drum mill’ by Jan-Hendrik Schöbel et al., RSC Mechanochem., 2025, 2, 224–229, https://doi.org/10.1039/D4MR00096J.

Correction for ‘Utilizing an attritor mill for solvent-free mechanochemical synthesis of rac-ibuprofen:nicotinamide co-crystals’ by Sarah Triller et al., RSC Mechanochem., 2025, 2, 538–543, https://doi.org/10.1039/D5MR00020C.

We report an efficient photo-contact electrification (CE) method for controlling the synthesis of pristine silver nanoparticles of different shapes, as one, two, and three-dimensional materials, notably rods, spicules and triangles. This uses a vortex fluidic device (VFD) which houses a rapidly rotating quartz tube tilted at 45° while the aqueous silver nitrate thin film is irradiated at 254 nm. The photo-CE associated with the mechanical energy imparted into the liquid in the microfluidic platform allows control of the size and shape of the nanoparticles, and some micron size particles, depending on the rotational speed of the tube and concentration of silver nitrate. Uniform shapes are generated with pristine surfaces in the absence of added reducing agents, with processing scalability under continuous flow. This synthetic method is also simple and cost-effective, and overall adheres to the principles of green chemistry.

The growth of tribofilms from the mechanochemical decomposition of lubricant additives is crucial to prevent wear of sliding metal surfaces. For some applications, such as electric vehicles and wind turbines, lubricants can be exposed to electric fields, which may affect tribofilm growth. Experimental tribometer results have shown conflicting results regarding antiwear tribofilm growth and wear under external electric potentials. Moreover, the effect of electric fields on the mechanochemical decomposition of lubricant additives remains unclear. Here, we use nonequilibrium molecular dynamics (NEMD) simulations to study the mechanochemical growth of a polyphosphate tribofilm from trialkyl phosphate molecules under external electrostatic fields. The decomposition rate of phosphate esters increases exponentially with the applied stress and temperature. The electric field generally accelerates the molecular decomposition, both by enhancing the interfacial stress and reducing the steric hindrance for nucleophilic substitution. The Bell model is used to analyse the electro-, mechano- and temperature-dependent decomposition process. Under weak electric fields, the activation energy for molecular decomposition increases due to the competition between electric field- and shear-induced deformations. For stronger fields, the activation energy decreases linearly with increased electric field strength and this dominates over the shear-induced molecular rotation. The resultant non-monotonic variation in the activation energy for molecular decomposition with electric field strength explains the conflicting effects of electric potential on tribofilm growth observed experimentally. The activation volume decreases linearly with increasing electric field strength, indicating a reduced dependence of the decomposition on shear stress as the electric field dominates. Asymmetric tribofilm growth is observed between surfaces with external electric fields, which is consistent with the experimental observations. This study presents atomistic insights for the coupling of electro- and mechano-catalysis of an industrially-important molecular decomposition process.